The invention relates to a circuit breaker of the kind described in the document EP-A-0,222,645, comprising at least one pair of contacts at least one of which is movable and can take with respect to the other contact a closed position corresponding to mechanical and electrical contact and an open position, this circuit breaker being of the type equipped with a closing device provided with an energy storage device.
A pole 10 of a known circuit breaker 1 of this type and its opening mechanism 20 have been represented in FIGS. 1 to 3. FIG. 4 represents a loading and closing mechanism 30 of this circuit breaker, the unloaded position. FIG. 5 represents the circuit breaker's loading and closing mechanism in the loaded position.
The pole 10 comprises in conventional manner a pair of breaking contacts 11, 12. The contact 11 is stationary and the contact 12 is mounted pivotally between an open position which can be seen in FIG. 1, in which it is separated from the stationary contact, and a closed position which can be seen in FIG. 3, in which mechanical and electrical contact between the contacts 11 and 12 is established. The pole 10 also comprises an arc extinguishing chamber 19 and a pair of main terminals 14, 15 extending outwards from the rear face of the circuit breaker 1 and designed to engage by means of engagement contacts on connection terminal strips. The circuit breaker 1 comprises a plurality of poles 10 arranged in parallel planes, perpendicular to a pole shaft 16 which is common to these poles. The closing or opening order of the poles is transmitted to each movable contact 12 by means of a connecting rod 13 operating in conjunction with a lever securedly affixed to the pole shaft 16.
The opening mechanism 20 comprises a toggle mechanism 21 with two small rods articulated on one another by a pivoting spindle. One of these rods is mechanically coupled to a crank 23 of the pole shaft common to all the poles, this crank moreover forming one of the levers operating in conjunction with the rods 13. The other rod is articulated in rotation on a trip hook 22 pivotally mounted on a fixed spindle. An opening spring 24 is secured between the crank 23 and a fixed securing pin and tends to return the crank 23 to its open position shown in FIG. 1, in the counter-clockwise direction in this figure. An opening catch 25 formed by a lever pivoting around a fixed spindle is controlled by an opening latch 26 in the shape of a half-moon. The catch 25 is biased by a spring in a direction in which it is moved away from the half-moon and towards the hook 22. The opening latch 26 is returned to its latched position. In other words, the half-moon is biased by a spring in a direction opposing rotation of the catch 25 as can be seen in FIGS. 2 and 3. A roller 27 arranged on the opening catch 25 between its ends is designed to operate in conjunction with a V-shaped recess of the trip hook 22, in the positions of FIGS. 2 and 3. The hook 22 is biased by a spring in a counter-clockwise direction in FIG. 1, tending to shorten the distance between the articulation axis of the toggle mechanism 21 on the hook 22 and the articulation axis of the toggle mechanism 21 on the crank 23.
The loading and closing mechanism 30 is represented in FIG. 4 in its unloaded state. This mechanism comprises a drive lever 31 pivotally mounted around a fixed spindle 32. A flexible energy storage device comprising at least one closing spring 34 is pivotally mounted on the side of one of its ends on a fixed point and on the side of the other of its ends to a finger of the drive lever 31. The drive lever bears a roller 33 designed to cooperate with a loading cam 46 keyed onto a shaft 41 of a drive mechanism. The cam 46 comprises a roller 47 designed to operate in conjunction with a closing ratchet 36 which is pivotally mounted around a fixed spindle 37. A closing latch 38 in the shape of a half-moon is designed to lock the ratchet 36 in the position of FIG. 5. This latch 38 is flexibly biased by a spring to its closed position. The ratchet 36 is itself biased by a spring to its latched position represented in FIG. 5.
The opening mechanism and the loading and closing mechanism are mounted on one or more flanges constituting a fixed support and the two planes of projection of FIGS. 1 to 3 on the one hand and of FIGS. 4 and 5 on the other hand are disposed approximately parallel to one another. A link between the opening mechanism and the loading and closing mechanism is achieved by a finger 39 securedly united to the drive lever 31 and designed to operate in conjunction with the toggle mechanism 21, this finger extending according to an axis essentially perpendicular to the sectional planes of FIGS. 1 and 4. The opening mechanism and the loading and closing mechanism are both provided with end of travel stops which can be seen in the figures.
The circuit breaker opening and closing sequences can be schematized from FIGS. 1 to 5. In FIG. 4, the loading and closing mechanism is in its unloaded state: the closing spring 34 is relaxed; the roller 47 is pressing against the closing ratchet 36; the closing half-moon is open and also operates in conjunction with the closing ratchet 36. Movement from the unloaded state of FIG. 4 to the loaded state of FIG. 5 is achieved by clockwise rotation of the shaft 41 and cam 46 in the figures. In a first stage, the roller 47 releases the ratchet 36 which moves due to the force of its return spring to the position represented in FIG. 5. At the same time, the closing latch 38 recloses due to the action of its return spring and latches the ratchet 36 in position. The cam 46, continuing its rotation, comes into contact with the roller 33 of the drive lever 31, driving the latter in clockwise rotation to the position of FIG. 5. In its rotation, the drive lever loads the spring 34. In the position reached in FIG. 5, the cam has passed a dead point and has become receiving: the roller 33 has reached a zone of the cam in which it biases the latter clockwise, whereas the ratchet 36 forms a stop for the roller 47 and opposes any movement in the clockwise direction. The mechanism is then loaded.
Impulse relaxation of the closing spring 34 is obtained by unlocking the latch 38. This unlocking in fact releases the ratchet 36 biased by the roller 47 of the cam 46. The cam 46, itself biased by the roller 33 of the drive lever 31, rotates clockwise and totally releases the roller 33, resulting in counter-clockwise impulse rotation of the drive lever due to the impulse of the relaxing spring 33. At the end of the closing spring relaxation phase the mechanism is in the position shown in FIG. 4.
The closing spring loading phase and relaxation phase can be performed whatever the state of the opening mechanism. During the loading phase, the finger 39 pivots clockwise around the spindle 32. In the opposite manner, during the relaxation phase, the finger 39 pivots counter-clockwise and returns to its previous position.
These pivotings of the finger 39 have different effects on the opening mechanism depending on whether the latter is initially open or closed.
The unloaded open switchgear apparatus is represented in FIG. 1. The finger 39 is then pressing against a recess of one of the rods of the toggle mechanism 21 and opposes counter-clockwise rotation of the hook 22 due to the biasing effect of its return spring. Rotation of the finger 39 during the loading phase releases the toggle mechanism 21 and the hook 22 which progressively move to the position represented in FIG. 2 due to the biasing effect of the return spring of the hook: the hook 22 has rotated counter-clockwise and the distance between the ends of the toggle mechanism has decreased. The hook, by operating in conjunction with the stop 27 of the catch 25, allows counter-clockwise rotation of the catch 25 due to the biasing effect of its return spring until the catch passes beyond the half-moon of the opening latch 26. The latch then recloses due to the biasing effect of its own return spring and prevents the opening catch 25 from returning in the clockwise direction. The hook 22, when it has completed its rotation, places itself in such a way that its V-shaped recess operates in conjunction with the stop 27 of the catch 25 and is blocked in position by the latter, as represented in FIG. 2. The opening mechanism is then in the loaded open position.
Relaxation of the closing spring causes, as has already been said, rotation of the finger 39 which follows a reverse trajectory to the previous one. In doing this, the finger 39 drives one of the small rods of the toggle mechanism 21. The hook 22 is blocked in position by the stop 27 of the opening catch 25. The articulation axis of the toggle mechanism 21 on the hook 22 therefore remains fixed and it is the articulation axis of the toggle mechanism on the crank 23 which is forced to move, thus moving the crank 23, pole shaft 16, levers, rods 13 and movable contacts 12 of the different poles to their closed position. The opening spring 24 is for its part automatically loaded when closing of the poles takes place due to the movement of its point of attachment to the crank 23. At the end of this phase, the switchgear apparatus is closed and unloaded. The opening mechanism is in the position represented in FIG. 3, with the finger 39 in its position shown by a broken line. The toggle mechanism 21 has moved slightly past its dead point, which means that the articulation axis between the toggle mechanism rods has passed from one side to the other of a plane containing the other two articulation axes of the toggle mechanism, that one of the rods is pressing against an end of travel stop 28 securedly affixed to the hook 22 and that there is no longer any cooperation between the finger 39 and the toggle mechanism 21.
If, from the unloaded closed position, the opening latch 26 is unlatched, the position is of FIG. 1 is reached in the following manner: opening of the half-moon of the latch 26 releases the opening catch 25 and consequently the hook 22. Due to the biasing of the opening spring 24, the toggle mechanism 21 biases the hook 22 both at the level of its common articulation with the hook 22 and at the level of the end of travel stop 28. This biasing results globally in a torque causing clockwise rotation of the hook 22, which lowers the articulation axis of the toggle mechanism on the hook, makes the toggle mechanism pass via its dead point again and enables it to fold back to the position of FIG. 1, the toggle mechanism 21 coming up against the stop formed by the finger 39 in the unloaded position.
Starting again from the unloaded closed position, the loading mechanism can also be reset whereas the poles remain closed, which moves the mechanism to its loaded closed position and the finger 39 to the position indicated by an unbroken line in FIG. 3. Following this resetting operation, opening of the opening latch moves the opening mechanism to the loaded open position of FIG. 2 by a sequence similar to the previously described opening sequence, except for the fact that the folding movement of the toggle mechanism is not stopped by the stop and can be pursued, driving with it the hook 22, which again enables counter-clockwise rotation of the catch 25 due to the biasing of its return spring, until the catch has passed the half-moon of the opening latch 26. The latch 26 then recloses due to the biasing of its return spring and the hook, on completing its rotation, replaces itself in the position represented in FIG. 2. The opening mechanism is then in the loaded open position.
It can therefore be seen that, from the loaded closed position of FIG. 3, it is possible to consecutively perform an opening which leads to the position of FIG. 2, a closing which leads to the position of FIG. 3, in broken lines, and an opening which leads to the position of FIG. 1, without resetting the loading device. This opening, closing, opening (OCO) sequence is characteristic of this type of circuit breaker.
The invention relates more precisely to this type of circuit breaker, when it is mounted in its plug-in version, that is to say integrated in a switchgear unit comprising a frame called the fixed frame, and a circuit breaker movable with respect to the fixed frame between an extracted position and a plugged-in position. The frame is generally box-shaped and comprises an opening on the front panel enabling the circuit breaker to be inserted, as well as slides for support and guiding thereof between the extracted position and the plugged-in position. The extracted position is that in which the circuit breaker can be removed from the frame slides. The plugged-in position is that in which the circuit breaker terminals are secured to the corresponding terminals of the frame, themselves connected to the electrical circuit, for example by an external busbar. Intermediate positions between the extracted position and the plugged-in position are generally distinguished, in particular, starting from the extracted position, a position called the plugged-out position in which no electrical contact exists between the circuit breaker and frame, but from which a kinematic transmission system becomes active for subsequent movement of the circuit breaker to the plugged-in position, and a position called the test position in which the main circuits of the circuit breaker, i.e. the terminals referred to above, are disconnected, but auxiliary electrical circuits are connected to the frame. Certain intermediate positions may be identical to one another or to the extreme positions: for example, the extracted position may be the same as the plugged-out position, or the plugged-out position be the same as the test position. The kinematic transmission system serving the purpose of moving the movable part of the circuit breaker between the plugged-out position and the plugged-in position is generally driven by a removable crank operated by the operator. It may also be motor-driven.
For this type of switchgear in its plug-in version, usage imposes that the handling operations enabling the circuit breaker to be extracted from its frame give rise to automatic sequences so that the circuit breaker at the end of the extraction phase is open and unloaded. This usage corresponds to a concern for preventing any risk of accident for the operator who may have to handle or reomve the circuit breaker.
Traditionally, to achieve this result, manufacturers ensure that the opening latch and closing latch are both placed in their unlatched position so long as the switchgear apparatus is not between the plugged-out position and the plugged-in position. A switchgear apparatus of this type is described for example in the document EP-A-0,227,586. This solution is not entirely satisfactory either from the accident risk prevention point of view or from the equipment reliability point of view.
From the equipment reliability point of view, it should be emphasized that the extraction sequence according to the state of the technique comprises two stages: the first is unlatching of the opening latch, the second unlatching of the closing latch whereas the opening latch is kept open. This second stage gives rise to an operating sequence, called no-load discharge or discharge on open poles, which differs from the sequences described hitherto. If the circuit breaker is previously in its loaded closed state, the opening order in fact moves it first of all to a loaded open state, which differs from that of FIG. 2 by the fact that the opening latch is kept in the unlatched position. The pole closing order, i.e. the closing latch unlatching order, then releases the roller 33 causing impulse rotation of the drive lever 31 and of its finger 39. Due to the absence of latching of the opening catch 25, the hook 22 is free in rotation and is moved directly to the position of FIG. 1. The excess kinetic energy is absorbed by the end of travel stops of the hook, whereas in a normal cycle, this stop only absorbs a small amount of energy. This no-load discharge therefore implies either that the switchgear unit be over-dimensioned or that its endurance be sacrificed.
In state of the technique equipment in the extracted position, the opening and closing latches are kept open. It is however always possible to operate the resetting lever which acts on the reloading cam. At the end of loading travel, when the roller 47 of the cam 46 comes into contact with the closing ratchet 36, no blocking of the cam occurs due to the fact that the ratchet is not blocked in rotation. Rotation of the cam is therefore pursued and a no-load discharge is obtained.